git: dc844e386896 - stable/12 - Fix libfetch out of bounds read.

[Gordon Tetlow]

The branch stable/12 has been updated by gordon:

URL: https://cgit.FreeBSD.org/src/commit/?id=dc844e386896f62a847d3294cd90b3412dcce9ca

commit dc844e386896f62a847d3294cd90b3412dcce9ca
Author:     Gordon Tetlow <gordon at FreeBSD.org>
AuthorDate: 2021-08-24 17:59:01 +0000
Commit:     Gordon Tetlow <gordon at FreeBSD.org>
CommitDate: 2021-08-24 17:59:53 +0000

    Fix libfetch out of bounds read.
    
    Approved by:    so
    Security:       SA-21:15.libfetch
    Security:       CVE-2021-36159
    
    (cherry picked from commit 3be62d49ae2b6f9050f39fe74210c88f35901fa5)
---
 lib/libfetch/ftp.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/libfetch/ftp.c b/lib/libfetch/ftp.c
index 9a546f3fecad..dfde6edce734 100644
--- a/lib/libfetch/ftp.c
+++ b/lib/libfetch/ftp.c
@@ -704,8 +704,11 @@ ftp_transfer(conn_t *conn, const char *oper, const char *file,
 				goto ouch;
 			}
 			l = (e == FTP_PASSIVE_MODE ? 6 : 21);
-			for (i = 0; *p && i < l; i++, p++)
+			for (i = 0; *p && i < l; i++, p++) {
 				addr[i] = strtol(p, &p, 10);
+				if (*p == '\0' && i < l - 1)
+					break;
+			}
 			if (i < l) {
 				e = FTP_PROTOCOL_ERROR;
 				goto ouch;